A new report came out today arguing for regulated legalisation, but it's going to take more than suggestions to achieve real policy change.

It's been almost 20 years since things looked like they were going to change. Rewind to 1997. Tony Blair's just been elected Prime Minister; the Union Jack is trendy and the phrase "Cool Britannia" isn't just something you'd see on a shit mug marketed at Spanish tourists.

It's September and the Independent on Sunday has just launched a six-month campaign to get people talking about legalising cannabis in the UK. In March of 1998, an estimated 15,000 to 25,000 people light up in Hyde Park for a pro-legalisation rally that makes its way to Trafalgar Square. Within years, the campaign and protest are basically all but forgotten, and every attempt since to bring lawmakers around is essentially shut down in its infancy, despite the rational points being made.

Yet again, another convincing case has been brought. Today, the Adam Smith Institute and drug policy innovation hub Volte Face released a joint report on the state of cannabis legislation in the UK. The report suggests that regulated legalisation is the way forward and could help Britain follow the current trend set recently by the US state of California, and previously by the likes of the Netherlands and Portugal. On top of that, the report estimates that the Treasury could stand to make up to £1 billion per year from a cannabis market with a potential annual worth of £6.8 billion.

"The current policy around cannabis in Britain is a messy patchwork of legislation intermittently enforced," writes journalist Boris Starling, the report's author. "It places political posturing above public health and tabloid values above humane ones."

What you're left with, the report continues, is a government strategy based around three pillars: "Reducing demand, particularly among vulnerable youths and/or those involved in the criminal justice system; restricting supply by tackling the organised crime gangs which supply drugs through importing them from abroad or growing/manufacturing them on British soil; and building recovery in communities through public health facilities and an attempt to understand and tackle the wider social circumstances which propel people to use drugs in the first place."

In the UK, the Home Office looks after cannabis strategy – and so it becomes a matter of law and order, rather than one of public health. One of the report's main recommendations is to switch the ownership of drugs strategy from the Home Office to the Department of Health, reshaping policy to centre on health within a regulated cannabis market rather than public order and crime in a system where the recreational use or sale of cannabis is considered illicit, immoral and criminal.

This is a sensible point, and one espoused by many with progressive views around drug legislation. Back in 2014, when Nick Clegg was Deputy Prime Minister, he said that "the first step is to recognise that drug use is primarily a health problem. Addicts need help, not locking up. It is nonsense to waste scarce resources on prison cells for cannabis users. Instead, these people should receive non-custodial sentences and addicts should get the treatment they need to stop using drugs. These reforms will ensure that drug users get the help they need and that taxpayers don't foot the bill for a system that doesn't work."

There's a huge body of evidence to suggest legalisation and regulation is the way forward – and a group of cross-party MPs are onside – but all of this means nothing if the people with the most power to affect legislation don't change their views. Everyone from the World Health Organisation to the United Nations Office on Drugs and Crime are cited as advocating a treatment-based approach rather than a criminal one, but making this shift is not likely to be a political priority for Theresa May – she is, after all, going to mostly end up remembered as the Brexit Prime Minister – and with the Conservatives firmly entrenched in government for the foreseeable future, it's unlikely we'll see much top-level progression from her way of thinking.

Earlier this year, before she took up the role, her views on drugs policy came under scrutiny. Clegg alleged in April that, as Home Secretary, May had tried to take sentences out of a Whitehall report on the link – or lack thereof – between tough drug laws and levels of illegal drug use. The report found that there was "no obvious" relationship between harsh drug laws and a deterrent effect on people's drug use, which then sparked further debate on why the UK isn't pursuing decriminalisation.

"This government has no plans to legalise cannabis," a Home Office spokesperson told VICE. "There is a substantial body of scientific and medical evidence to show that cannabis is a harmful drug which can damage people's mental and physical health. The UK's approach on drugs remains clear – we must prevent drug use in our communities and support people dependent on drugs through treatment and recovery."

"We have seen a reduction in drug misuse among adults and young people compared with a decade ago," they continued, "and more adults are leaving treatment successfully compared to 2009/2010. The proportion of adults aged 16 to 59 using cannabis in the last year in England and Wales has declined from 9.6 percent in 2004/2005 to 6.5 percent in 2015/2016 – with cannabis use amongst young adults aged 16-24 and young people aged 11-15 following a similar pattern."

So not a lot of hope there, then. Mind you, the report stands behind the notion that policy in the UK could change if it's swept along in a worldwide tide that's already seen "green economies" launch in certain US states. And if most countries have found a way to standardise the markets for tobacco and alcohol, Starling writes, cannabis shouldn't be impossible to handle:

"Already it is clear that keeping cannabis illegal merely because it is harmful does not square with the government's policies on alcohol and tobacco. Alcohol and tobacco are legal because they have always been, because any attempts at prohibition would be totally unworkable, and because they generate billions of pounds in revenue for the Treasury every year. Were cannabis made legal, it would not be long before similar considerations would apply to it too. The British are very good at grumbling about change when it happens and then accepting it as though it had always been thus."